The invention relates to brake bands, friction linings and analogous friction generating devices or bodies which can be utilized in automatic transmissions and/or friction clutches of motor vehicles or for other purposes. The invention also relates to a method of making such friction generating bodies. Friction generating bodies of the above outlined character normally constitute laminates or sandwiches wherein a metallic first layer or substrate carries a second layer consisting at least in part of a friction generating material.
Brake bands wherein a metallic layer carries a layer of friction generating material are disclosed, for example, in the aforementioned commonly owned copending patent application Ser. No. 07/952,582, of Johann Jxc3xa4ckel et al. and in U.S. Pat. No. 4,602,706 granted Jul. 29, 1986 to John C. Blinks et al. for xe2x80x9cDouble wrap brake bandxe2x80x9d. The disclosures of Jxc3xa4ckel et al. and of the patent to Blinks et al. are incorporated herein by reference.
Friction generating bodies in the form of substantially disc-shaped circular friction clutch linings are disclosed, for example, in the German Auslegeschrift No. 1 210 686. The friction generating layer of the friction lining which is disclosed in this German publication is glued to the metallic layer or substrate. A drawback of the just described friction linings is that, when the friction clutch which embodies the friction lining of the German publication is heated, the thermally induced expansion of the metallic layer departs from the thermally induced expansion of the friction generating layer. The friction lining then acts not unlike a bimetallic element, i.e., the friction lining undergoes undue and highly undesirable deformation. Moreover, the bond between the two layers of such friction lining is subjected to highly pronounced separating stresses.
An object of the invention is to provide a relatively simple and inexpensive friction generating device or body wherein a metallic layer is affixed to and supports a friction generating layer.
Another object of the invention is to provide a novel and improved brake band for use in automatic transmissions of motor vehicles.
A further object of the invention is to provide a friction lining for use in clutch plates or clutch discs of friction clutches for motor vehicles.
An additional object of the invention is to provide a novel and improved method of making a friction generating device or body of the above outlined character.
Still another object of the invention is to construct and assemble the friction generating body in such a way that the metallic layer is movable to an optimum position relative to the friction generating layer and/or vice versa.
A further object of the invention is to provide a method of assembling a friction generating device or body of the above outlined character in such a way that any weakening of the one and/or the other layer takes place subsequent to affixing of the second layer to the first layer.
Another object of the invention is to provide a novel and improved method of making incisions into the one and/or the other layer of the friction generating body.
An additional object of the invention is to provide a novel and improved method of converting the above outlined friction generating body into a multiple wrap brake band.
Still another object of the invention is to provide a novel and improved method of converting the above outlined friction generating body into a friction lining for use in the clutch plates or clutch discs of friction clutches in motor vehicles.
A further object of the invention is to provide novel and improved means for making incisions in the above outlined friction generating body.
Another object of the invention is to provide novel and improved means for making incisions in the friction generating layer of the above outlined body.
An additional object of the invention is to provide a transmission which embodies one or more friction generating bodies of the above outlined character.
Still another object of the invention is to provide a clutch plate or clutch disc which embodies the above outlined friction generating body.
One feature of the present invention resides in the provision of a shaped friction generating body which can be used as a brake band (e.g., in automatic transmissions), as a friction lining in the clutch plate or clutch disc of a friction clutch for motor vehicles, or for other purposes. The improved friction generating body comprises a metallic first layer (e.g., a layer of steel) having a first side and a second side, and a second layer which is affixed (e.g., bonded) to one side of the first layer and consists at least in part of a friction generating material (e.g., a material which is used to make brake linings for incorporation into the clutch plates or clutch discs of friction clutches for motor vehicles). In accordance with a feature of the invention, at least one of the two layers has at least one incision or cut resulting from the application of at least one high-energy stream such as a laser beam, an electron beam or a liquid jet.
The layers can together constitute or form part of a friction lining for use in clutch plates or clutch discs. The at least one incision can be provided in and can extend at least substantially through the second layer. The at least one stream for the making of such incision can be a laser beam. The at least one incision can extend substantially radially or substantially chordally of the friction lining, and at least the radial incision can extend at least substantially all the way from the center to the periphery of the friction lining.
The two layers can jointly constitute a substantially cylindrical brake band for use in conjunction with a brake drum or clutch drums. One or more laser beams can be used to provide the cylindrical brake band with one or more incisions.
The second layer has a first side adjacent the one side of the first layer and a second side, and the at least one incision can extend from the second side toward the first side of the second layer (e.g., toward but short of the first side, all the way to the first side, beyond the first side and into the first layer, or all the way to the other side of the first layer).
The first layer can at least partially surround the second layer. For example, if the two layers are hollow cylinders, the hollow cylinder which constitutes the first layer can surround the entire hollow cylinder which constitutes the second layer.
The second layer can include at least one portion of reduced thickness (e.g., zero thickness) as a result of material removal, e.g., by subliming and/or by melting. Such subliming and/or melting can be carried out in an atmosphere of inert gas. Any remnant or remnants of material which has been removed from the second layer (e.g., by subliming and/or by melting) but tends to adhere to the one and/or the other layer can be separated from the layers as a result of entrainment with one or more streams of a gaseous fluid, e.g., air or nitrogen.
The at least one incision can be formed as a result of the application of one or more fluids.
The at least one incision can extend through the second layer and thence from the one side toward the other side of the first layer, e.g., toward but short of the other side or all the way to the other side of the first layer. Such incision can be formed as a result of cutting with a laser beam in the presence of oxygen.
The at least one incision can extend through one of the layers and into the other layer as a result of cutting with one or more high-pressure laser beams.
The at least one stream can be an uninterrupted laser beam or a pulsating laser beam.
Another feature of the invention resides in the provision of a friction lining for use in the clutch plates or clutch discs of friction clutches, particularly in motor vehicles. The friction lining comprises a metallic first layer having a first side and a second side, and a second layer which is affixed (e.g., soldered, brazed, welded or glued) to one side of the first layer and consists at least in part of a friction generating material. At least the second layer has at least one incision which is formed therein as a result of the application of at least one high-energy stream, particularly one or more laser beams.
A further feature of the invention resides in the provision of a substantially cylindrical brake band (e.g., a multiple wrap brake band) which comprises a metallic first layer having a first side and a second side, and a second layer applied (e.g., glued) to one side of the first layer and consisting at least in part of a suitable friction generating material. At least one of the two layers has at least one incision or cut (e.g., in the form of a circumferentially extending slot or slit, a substantially U-shaped slit or cut, or one or more substantially L-shaped cuts or slits) as a result of the application of at least one high-energy stream, for example, one or more laser beams, one or more electron beams or one or more liquid jets.
An additional feature of the invention resides in the provision of a method of making a shaped friction generating body. The improved method comprises the steps of bonding one side of a metallic first layer to one side of a second layer which consists at least in part of a friction generating material, and providing at least one of these layers with at least one incision (e.g., a slit, a slot or a cut) including subjecting the at least one layer to the action of at least one high-energy stream, for example, to the action of one or more laser beams, one or more electron beams or one or more liquid jets.
At least one of the layers can resemble or constitute a disc, and the at least one incision can be provided in the second layer. The at least one stream which is used to make such incision can be a laser beam. The at least one incision can extend at least substantially radially of the disc (e.g., all the way or nearly all the way from the center to the periphery of such disc) or it can extend substantially chordally of the disc.
The method can include the steps of imparting to the layers the shape of hollow cylinders one of which surrounds the other cylinder. The incision or incisions in at least one layer of such hollow cylindrical body is preferably made by resorting to one or more laser beams.
The step of making the at least one incision preferably includes directing the at least one stream against the other (exposed) side of the second layer. If the body is a hollow cylinder, the at least one layer preferably constitutes that cylinder which is surrounded by the other cylinder so that it has an exposed other side which is surrounded by the one side and by the other cylinder. The step of providing at least one incision preferably includes directing one or more streams against the exposed other side of the at least one layer (inner cylinder).
The method can further comprise the step of removing at least one portion of the second layer from the first layer. The removing step can comprise subliming and/or melting the at least one portion of the second layer. Such removing step can be carried out in an inert gas atmosphere. Remnants of the removed portion or portions of the second layer, which often tend to adhere to at least one of the layers can be separated from such layers, e.g., by entraining the remnants with at least one stream of a gaseous fluid such as air or nitrogen.
The step of providing at least one incision can be carried out in the presence of one or more fluids.
The incising step can include directing the at least one stream against the other (exposed) side of the second layer.
It is often preferred to carry out the incising step by resorting to laser beam cutting with oxygen.
Regardless of whether the body is to be provided with one, two or more incisions, the providing step can include simultaneously directing a plurality of laser beams against the other side of the second layer to form a plurality of incisions each of which can extend through the second layer and into the first layer (e.g., toward but short of the other side of the first layer or all the way to the other side of the first layer).
The step of providing at least one incision can include directing against the other side of the at least one layer one or more high pressure laser beams to extend the at least one incision through the at least one layer and into the other layer (e.g., partially through or all the way through the other layer).
The at least one stream can constitute a continuous laser beam or a pulsating laser beam.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved friction generating body itself, however, both as to its construction and the method of making the same, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.